Watch: US doctors successfully test a pig kidney transplant on a human patient 

A pig kidney has been transplanted into a person for the first time without causing rapid rejection by the recipient's immune system, a potentially significant development that might ultimately help ease a critical scarcity of human organs for transplant.

The operation was performed at NYU Langone Health in New York City and entailed the use of a pig whose genes had been changed such that its tissues no longer carried a chemical known to induce an almost instantaneous rejection. 

Pigs have been the most recent focus of research to solve the organ scarcity, but a sugar in their cells that is alien to the human body causes rapid organ rejection.

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The kidney used in this experiment originated from a gene-edited animal that was designed to remove that sugar while avoiding an immune system attack.

Surgeons connected the pig kidney to a pair of major blood arteries outside the body of a deceased recipient and monitored it for two days.

The kidney fulfilled its job — filtering trash and producing urine – without causing rejection. 

The idea of animal-to-human transplants, also known as xenotransplantation, dates back to the 17th century, when fumbling efforts to utilise animal blood for transfusions were made.

By the twentieth century, doctors began attempting baboon organ transplants into people, most famously Baby Fae, a dying child who lived 21 days with a baboon heart.

With little long-term success and much public outrage, scientists shifted their focus from monkeys to pigs, tampering with their DNA to bridge the species divide.

Pigs have a competitive edge over monkeys and apes.

Because they are grown for food, utilising them as organs poses less ethical problems.

Pigs have big litters, short gestation periods, and organs that are similar to those of humans. 

According to Montgomery, a heart transplant recipient, the NYU kidney transplant experiment should pave the way for studies in patients with end-stage renal failure in the next year or two.

The method may be tested as a short-term treatment for severely ill patients until a human kidney becomes available, or as a permanent graft in such studies.

The present study used a single transplant and the kidney was only left in place for three days, so any future studies are likely to reveal additional hurdles that will need to be addressed, according to Montgomery.

Patients with a low chance of getting a human kidney and/or a bad prognosis on dialysis would most likely be eligible.

(With inputs from agencies)